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What are .nfsXXXX files and how do I delete them?

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Applies to

NFS

Answer

What are .nfsXXXX files and how do I delete them?

Files with a naming convention like .nfsXXXX are created by NFSv3 clients when a file that is currently opened on a client is deleted by that client. The client renames the file to .nfsXXXX which discourages other clients/processes from utilizing the file. The client that does the rename should delete the file once it's been closed by the client process. This delete might not occur if the client is rebooted or the process that would issue the delete is terminated.

These files are not generated by an ONTAP process and are only created in response to client requests.

NFSv4 clients do not see this issue due to the statefulness of the protocol.

Finding the NFS client and process using a .nfsxxxx file may be very time consuming. It would require checking every process on every NFS client that could be accessing the NFS share containing the file. A utility such as lsof may be used to determine the process using the .nfsxxxx file. To prevent .nfsXXXX files from being created, do not remove a file when it is open. If the .nfsxxxx file is determined to no longer be in use then it may be removed. If a remove results in a new .nfsxxxx file then a process on that NFS client has the file open.

Demonstration for creating and removing .nfsxxxx files:

  1. From the NFS client, create a file in the mounted NFS share and open it with the tail command. Suspend the process with ctrl-z or open a new terminal to complete the rest of the demonstration.

    shell# echo test > foo
    shell# tail -f foo
    test
    ^Z
    [1]+ Stopped tail -f foo

     
  2. Remove the file foo to make the NFS client create the .nfsxxxx file.

    shell# rm foo
    shell# ls -A
    .nfs5ACF

     
  3. Observe that subsequent rm commands only make the NFS client rename the file again.

    shell# rm .nfs5ACF
    shell# ls -A
    .nfs6ACF

     
  4. Locate the process that has the file open using lsof or fuser.

    shell# lsof ./.nfs6ACF
    COMMAND   PID USER   FD   TYPE DEVICE  SIZE NODE NAME
    tail    25725 root    3r   REG    8,1 27603 6647 .nfs6ACF


    shell# fuser .nfs6ACF
    .nfs6ACF 25725o

  5. Finally, kill the process holding the file open and observe that the .nfsxxx file is now removed.

    shell# kill 25725


    shell# ls -al
    total x
    drwxr-sr-x  2 root src    400 Mar 29 15:39 .
    drwxrwsr-x 36 root src   3336 Mar 21 09:37 .

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